The invention relates to magnetoelectronic components and to a measurement method, in the execution of which these components can be employed.
Magnetic shift registers, which are also known as “race track memory”, are magnetic memory devices that combine the robustness of flash memory, the speed of DRAM memory as well as the reversibility and non-volatility of hard drives. Such a shift register is known from (S. S. P. Parkin, M. Hayashi, L. Thomas, “Magnetic Domain Wall Racetrack Memory”, Science 320, 190 (2008)). Changes in magnetization, and thus domain walls, are introduced in oblong, ferromagnetic memory structures and pass through the memory structures longitudinally. This process takes advantage of an effect known as the spin transfer effect, as a result of which magnetic domain walls can be moved in thin memory structures in a controlled manner, along these memory structures, by applying electric currents. As is customary for hard drives, digital data is encoded into the distance between two consecutive domain walls.
Mobile domain walls play a role not only in storing, but also in processing information. Logic elements that process movable domain walls as information units are known from (D. A. Allwood, G. Xiong, C. C. Faulkner, D. Atkinson, D. Petit, R. P. Cowburn, “Magnetic Domain Wall Logic”, Science 309, 1688 (2005)). Domain walls were proposed in (R. Hertel, W. Wulfhekel, J. Kirschner, “Domain-wall induced phase shift in Spin Waves”, Physical Review Letters 93, 257202 (2004)) as information units in logic elements based on the propagation of spin waves along thin magnetic strips.
A basic prerequisite for the aforementioned elements to function is the fast and controlled motion of domain walls along thin magnetic strips. The disadvantage, however, is the velocity at which the domain walls can move in the memory structures, or in the logic elements, is restricted to several 100 m/s. as a result of the Walker limit (N. L. Schryer, L. R. Walker, “The motion of 180° domain walls in uniform dc magnetic fields”, Journal of Applied Physics 45, 5406 (1974)). Above the maximum velocity defined by the Walker limit, cyclic, structural changes in the magnetization take place in the domain walls, putting the integrity of the stored or processed information at risk and drastically reducing the storage or processing rate (M. Kläui, P.-O. Jubert, R. Allenspach, A. Bischof, J. A. C. Bland, G. Faini, U. Rudiger, C. A. F. Vaz, L. Vila, C. Vouille, “Direct observation of domain-wall configurations transformed by spin currents”, Physical Review Letters 95, 026601 (2005)).